Clove Hitch is use to tie rope to
a pipe or a 2x4 and a host of other things. It will do a decent job of
grabbing onto the pipe without too much slipping. This is the knot that
is use in Hemp Houses to hang the pipe battens. (this photo is missing
the double half hitches. See below)

Start with your rope around the pipe.

Take a wrap.

The second wrap is placed over the first.

The free end of the rope goes through the second wrap.

Once the free end is through, pull it tight.

This is a finished Clove Hitch. For safety sake, add the next couple of steps.

This is a Half Hitch. Take the free end and take a wrap around the load line, then pass it through itself.

Pull it tight.

Do that again.

This is what the final knot will look like. At this point, you should consider taping the loose end up to the load line.

This is a Double Half Hitch by itself. See above to learn to tie this.